Investigations on remote laser beam welding of dissimilar joints of aluminum alloys and steel with varying sheet thicknesses for car body construction

Abstract

For lightweight construction, different steel and aluminum materials with various thicknesses can be welded together, depending on the dimensions and the individual functions of the workpiece. Specifically for frame and body construction, remote laser beam welding has been established as a suitable and efficient joining method for similar material seams for several years. In contrast to joining similar materials, thermal joining of steel and aluminum alloys includes different technological challenges due to the formation of hard and brittle intermetallic phases, which decreases the strength and the formability of the dissimilar joints. In the context of these requirements, the presented results show, besides the influence of different steel materials, particularly the influence of different sheet thicknesses and thickness ratios on the appropriate process parameters for remote laser beam welded lap joints of steel and aluminum alloys, respectively. Different thickness ratios, process parameters, and material properties affect the geometrical formation of the weld seam regarding penetration depth tE and weld width b, which mainly influences the composition of the molten bath and accordingly the transmittable forces. Within the scope of the presented investigations, dissimilar joints of the steel materials such as HX220LAD+Z100, 22MnB5+AS150, and 1.4301 as well as the aluminum alloy such as AA6016-T4 are characterized. Among others, the influences of the energy per unit length, material grade, and sheet thickness ratio on the achievable strengths were analyzed. The characterization of the dissimilar joints includes tensile shear tests and metallographic analyses, depending on the energy per unit length.

A Review: Laser Welding of Dissimilar Materials (Al/Fe, Al/Ti, Al/Cu)—Methods and Techniques, Microstructure and Properties

“…Other papers on the topic of laser welding of steel and aluminum describe the choice of filler material [ 34 , 35 , 36 , 37 ], shielding gas [ 38 ], the application of coatings on the metals to be joined [ 35 , 36 , 37 , 38 , 39 , 40 , 41 ], the use of double-beam laser welding [ 42 , 43 , 44 ], or the use of remote high-speed welding [ 45 , 46 ] ( Table 4 ).…”

“…Nikulina A.A. et al in [ 64 ] use significantly higher laser welding speeds (70–100 mm/s) in comparison with the above works (11–17 mm/s) [ 45 , 46 , 47 , 48 ]. The effect of the welding speed and the level of heat input when butt welding the titanium alloy VT6S (3 mm thick) and aluminum alloy AA1424 (4 mm thick) was investigated.…”

Advances in macro-scale laser processing

“…This kind of laser source can be used for several processes in the field of laser material processing such as e.g. high power welding processes [22,23,236] and laser-arc hybrid welding processes [131,233,234]. The high beam quality described by a small beam parameter product (BPP ~ 2 mm•mrad for TruDisk 2000 with an output power of 2 kW [265]), allows for the usage of an optical waveguide with a minimal diameter of 50 µm and thus a beam focus diameter on the work piece in the same size.…”

Recent Developments in Laser Welding of Aluminum Alloys to Steel

“…Finally, they found the best mechanical performance for intermediate levels of laser power and spot diameter, in which a compromise between wettability and microstructure was reached. Laser power and spot diameter were also studied by Seffer et al [61,62] and Lahdo et al [63]. In these works, linear energy density was considered, and its influence on weld geometry and microstructures was studied.…”